The audiogenically seizure susceptible rat is an excellent experimental model of epilepsy. The animals have a genetically determined lesion which lies at some site along the auditory pathway. The susceptibility and severity of seizure in any one animal is constant over many months, and convulsions are only produced when the animal is exposed to an appropriate sound stimulus. We intend to use the model to study the function of inhibitory and excitatory amino acids in the pathogenesis and treatment of epilepsy. Anatomical structures along the auditory pathway will be isolated and amino acid content determined. Similar analyses will be performed on samples obtained from animals immediately prior to and during convulsions, in order to elucidate the changes occurring during seizure and the sequence in which they occur. The prolonged anticonvulsant action of taurine and GABA will be examined by searching for changes in free amino acid content with time in brain areas into which the two inhibitory amino acids were injected. A correlation between the anticonvulsant effect of taurine and GABA and alterations in the concentration of certain amino acids will be sought. Pharmacological effects of amino acids, including taurine and GABA will be studied by the placement of indwelling electrode-cannulae units in selected sites in and along the auditory pathway. This will allow study of specific effects at the site of injection without the problem of general behavioral effects which are obtained when substances are administered into the cerebral ventricles. The information obtained will be of general applicability in the understanding of the pathological changes that occur during the genesis and spread of epileptic seizures.